1. Field of the Invention
The invention relates generally to the semiconductor power devices. More particularly, this invention relates to an improved and novel manufacturing process and device configuration for providing the MOSFET device with trench gates having thick bottom trench oxide or split gate by applying high density plasma based manufacturing processes with reduced number of masks.
2. Description of the Related Art
In order to reduce the power consumptions and to increase the switching speed of a power semiconductor power device, it is desirable to further reduce the gate capacitance. Generally, in a trench gate MOSFET device, a reduced gate capacitance is achieved by forming a thick oxide layer on the trench bottom of the trench gate. Alternately, the trench gate is formed as a split gate to reduce the gate capacitance. However, in order to form a thick oxide layer on the trench bottom or a split gate with split and mutually insulated bottom and top gate segment in the trench typically require additional processing steps. These additional processing steps may adversely affect the device production yields and costs and further reduce the device reliability due to the potential errors that may be introduced in carrying out the more complicate manufacturing processes.
Therefore, a need still exists in the art of power semiconductor device design and manufacture to provide new manufacturing method and device configuration in forming the power devices such that the above discussed problems and limitations can be resolved. It is desirable to simplify the manufacturing processes in forming the thick oxide layer on the bottom of the trench gate. Alternately, it is further desirable to simplify the processes in forming the split gate in the trench of a semiconductor power device such that the technical limitations can be resolved.